Identifying declines in waterbirds: The effects of missing data, population variability and count period on the interpretation of long-term survey data

To manage and conserve wildlife populations effectively it is necessary to use methods that identify the often non-linear trends in populations, have an inbuilt assessment of trend quality and can analyse count data from a range of spatial scales. We present a method of trend analysis using generalised additive models. These produce smoothed indices of abundance that can be used to assess population change from one or more sites or time periods, with any number of estimates of abundance per index period. We apply this method to count data collected under the Wetland Bird Survey, a national scheme that monitors waterbirds in the United Kingdom. To highlight declining populations, ‘alerts’ were raised if the population decline was equal to or greater than 50%. Significance was determined using bootstrapped confidence intervals for analyses that included many sites, or a novel Monte-Carlo method for single site analyses. The impact of missing data, species count variability and the number of months used to calculate the population change was greater at individual sites than for national datasets, which were relatively insensitive to changes in the above parameters. For single sites it is essential that three or more counts be made per index period if reliable estimates of population change are required. We propose that the method presented could be applied to a wide range of national or other monitoring schemes for a variety of taxa.     

Impact of livestock and settlement on the large mammalian wildlife of Bale Mountains National Park, southern Ethiopia

Large mammals, both wild and domestic, were censused in four study areas in Bale Mountains National Park (BMNP), southern Ethiopia, from April until August 1997, using established road counts, horse-back counts and systematic transects, a new approach to censusing large mammals in BMNP. Data collected since 1983 were also examined to indicate trends in mammalian abundance. Civil unrest following the government changeover in 1991 disrupted management of BMNP, leading to an increase in human settlement and livestock densities. The effect of these factors on BMNP's wildlife is assessed and discussed. Most large mammalian wildlife has declined since 1983 but signs of recovery for some species in recent years are positive. The fates of two charismatic endemics are emphasised. BMNP's current population of mountain nyala (Tragelaphus buxtoni, an endangered antelope) was estimated to be between 1100 and 1300. This is lower than estimates for the late 1980s, but shows an increase from very low levels recorded following social turmoil during the government changeover in 1991. Data on the Ethiopian wolf (Canis simensis, a critically endangered canid) also indicate positive trends in abundance, following severe declines between 1989 and 1992 due to rabies epizootics. Action to reduce human utilisation of parts of BMNP is urgently required to prevent further degradation of the environment and to safeguard the future of both the mountain nyala and Ethiopian wolf.     

我国黑木耳出口价格波动特征分析

以2017年1月—2021年7月我国黑木耳出口到世界的月度平均价格作为研究对象,采用Census-X12季节调整法和H-P滤波法将黑木耳的出口价格波动分解为季节性特征、不规则特征、循环特征和趋势特征4种类型.研究发现,黑木耳出口价格总体呈下降趋势,季节性特征显著,无明显的循环周期且不规则特征未出现减缓态势.为进一步稳定...     

土地利用变更调查成果在地理国情普查地表覆盖数据更新中的应用

以常德市汉寿县为研究区域,主要分析土地利用变更调查成果在地理国情普查地表覆盖数据更新中的适应性,通过对比土地利用变更调查与地理国情普查二者成果之间分类的差异和相似性,分析土地利用变更调查成果与地理国情普查成果之间的差异性和相似性,论证土地利用变更调查成果应用于地理国情普查地表覆盖数据更新的可行性。结果表明:土地利用变更调查成果部分可以作为地理国情普查地表覆盖更新疑似靶区,并用作重点区域,但是受时相性的差异影响,难以保证地表覆盖数据更新到位。     

Changes in visits to green spaces due to the COVID-19 pandemic: Focusing on the proportion of repeat visitors and the distances between green spaces and visitors’ places of residences

Through a quantitative approach, this study aimed to clarify the changes in the number of visitors and visits to green spaces according to green space type before and after the COVID-19 pandemic. We explored the changes in the proportion of repeat visitors and the distance between green spaces and visitors’ places of residence. We used KDDI Location Analyzer, which performs novel analysis using mobile phone GPS and census data. The study area included 10 target sites (urban parks and nature trails in the backcountry) located in the Sapporo metropolitan area in Japan. The survey period included snow-free seasons from 2019 to 2021, and 2019 was considered the period “before the pandemic.” The results revealed that the number of visits during the pandemic increased compared with those before the pandemic, except for those of urban parks near the city center. In 2020, the proportion of repeat visitors increased for all 10 target sites. In addition, since the outbreak of the pandemic, distances between all urban parks and visitors’ residences decreased. The same trend was observed for nature trails in the backcountry close to the city center. These findings indicate a generally decreasing trend in the number of visits to green spaces as many people have been refraining from visiting the site since the outbreak of the pandemic. Contrastingly, the number of visits by repeat visitors who reside close to the target sites has increased in some cases, which compensated for the general decreases.     

基于Census变换的双目视觉作物行识别方法

针对基于双目视觉技术的作物行识别算法在复杂农田环境下,立体匹配精度低、图像处理速度慢等问题,该文提出了一种基于Census变换的作物行识别算法。该方法运用改进的超绿-超红方法灰度化图像,以提取绿色作物行特征;采用最小核值相似算子检测作物行特征角点,以准确描述作物行轮廓信息;运用基于Census变换的立体匹配方法计算角点对应的最优视差,并根据平行双目视觉定位原理计算角点的空间坐标;根据作物行生长高度及种植规律,通过高程及宽度阈值提取有效的作物行特征点并检测作物行数量;运用主成分分析法拟合作物行中心线。采用无干扰、阴影、杂草及地头环境下的棉田视频对算法进行对比试验。试验结果表明,对于该文算法,在非地头环境下,作物行中心线的正确识别率不小于92.58%,平均偏差角度的绝对值不大于1.166°、偏差角度的标准差不大于2.628°;图像处理时间的平均值不大于0.293 s、标准差不大于0.025 s,能够满足田间导航作业的定位精度及实时性要求。     

不同锌添加量对生长期雄性梅花鹿消化率及血液理化指标的影响

旨在研究不同锌水平日粮对生长期雄性梅花鹿饲料消化率和血液理化指标的影响。选取20头生长期雄性梅花鹿,随机分为5组。A为对照组,饲喂基础日粮;B、C、D、E组锌的添加水平分别为5mg/kg、15mg/kg、40mg/kg、100mg/kg,试验期90d。结果表明：（1）不同锌水平日粮对生长期雄性梅花鹿饲料干物质、粗蛋白质、粗脂肪、中性洗涤纤维和钙、磷的消化率均比A组有增强的趋势,但除中性洗涤纤维外,其它均未达到统计学差异显著水平（P〉0.05）。（2）不同锌水平日粮对生长期雄性梅花鹿血清锌和碱性磷酸酶活性影响极显著（P〈0.01）。（3）不同锌水平日粮对生长期雄性梅花鹿血清丙氨酸氨基转移酶、冬氨酸氨基转移酶和磷酸肌酸酶活性均有影响,但未达到统计学显著水平（P〉0.05）;对血清总蛋白、白蛋白和球蛋白的水平有随日粮加锌量的不同而呈增加趋势,但未达到统计学显著水平（P〉0.05）。综合不同锌水平试验鹿生理生化指标的变化,本次试验研究表明：锌的适宜添加量为15mg/kg。     

两次全国污染源普查结果对比分析

本文基于全国第一次和第二次污染源普查结果,分析了我国十年来（2007年至2017年）各类污染物的排放、污染物处理设施的发展状况以及对污染物的消减情况。全国第二次污染普查（后简称“二污普”）较全国第一次污染源普查（后简称“一污普”）相比,主要水体污染物（化学需氧量、氨氮、总氮、总磷、重金属和石油类）的排放量分别减少29.2%、44.3%、35.7%、25.5%、79.8%与99.0%;大气污染物（二氧化硫）排放量减少70.0%;一般工业固体废物倾倒丢弃量减少96.8%,但危险废物的产生量了增加43.9%,因利用和处理量小于产生量,导致有大量危险废物堆积。总体而言,我国污染防治整体取得显著成就。在此基础上,应依据目前污染源普查结果采取科学合理的污染物防控措施,进一步推动工农业绿色持续发展。     

Observations on the Behaviour of Vervet Monkeys Cercopithecus Aethiops

A series of investigations on the vertical migration behaviour of estuarine zooplankton have been carried out in recent years. Several of these investigations have been carried out in collaboration with other zoologists and the detailed findings are being published separately. The work is reviewed here and an attempt is made to draw some general conclusions regarding the behaviour patterns observed. Attention is concentrated particularly on the behaviour of the copepod Pseudodiaptomus, Aspects investigated include behaviour in the field under natural conditions, light reactions and swimming speeds in the laboratory, reactions to layers of low salinity water, the role of endogenous rhythm in this behaviour and the significance of these behaviour patterns to the organisms.     

烟叶生产户籍化管理初探

现行的烟叶生产主要是单纯地对烟农进行技术指导,是一种粗放型的管理模式,造成了管理松散、物资严重流失等一系列问题.通过计算机管理系统的开发与尝试,对烟农实行户籍化管理,对职工实行岗位责任制,制定了一套行之有效的考评、监督、管理办法,取得了明显的效果.笔者提出了实施烟叶生产户籍化管理的必要性和进一步完善的措施.